This application makes reference to, incorporates the same herein, and claims all benefits accruing under 35 U.S.C. xc2xa7119 from three applications for SHEET FEEDING APPARATUS AND METHOD FOR IMAGE FORMING MACHINE earlier filed in the Korean Industrial Property Office on the Apr. 30th, 1998 and there duly assigned Ser. No. 15725/1998, for SHEET FEEDING APPARATUS AND METHOD FOR IMAGE FORMING MACHINE earlier filed in the Korean Industrial Property Office on the Apr. 30th, 1998 and there duly assigned Serial No. 15727/1998, and for SHEET FEEDING APPARATUS AND METHOD FOR IMAGE FORMING MACHINE earlier filed in the Korean Industrial Property Office on the Apr. 30th, 1998 and there duly assigned Serial No. 15728/1998.
1. Field of the Invention
The present invention relates to an image forming apparatus such as an ink-jet printer, and more particularly, to a sheet feeding technique for an image forming apparatus using a movement of a carriage as a driving power source, with which an ink-cartridge is mounted and which is reciprocated on a paper to print an image, in order to automatically feed a single sheet of paper on a printing apparatus of the image forming apparatus.
2. Description of the Related Art
Generally, papers are used in an image forming apparatus such as an ink-jet printer and facsimile machine, and so forth. The image forming apparatus is provided with a sheet feeding apparatus including a paper separating unit for feeding single sheets of paper.
The paper separating unit can be classified into two types. One is a finger type unit which employs a finger member for separating the papers, and the other is a pad type unit which employs a friction pad for separating the papers. However, in both types of units, a separate device, such as a cam, is provided so that the units operate by themselves.
In the paper separating unit for separating and feeding single sheets of paper, as mentioned to above, the finger type unit is mainly used, since its structure is comparatively simple. However, the finger type unit has a problem is that its accuracy in separating the papers into a single sheet is relatively low. This problem results in a sheet feeding error by feeding two or more sheets of paper, thereby causing a paper jam in the image forming apparatus.
In addition, the pad type unit has a problem in that, since the unit itself must have a separate driving means, the structure thereof is very complex and further the cost is high.
Moreover, an image forming apparatus such as an ink-jet printer employs a sheet feeding mechanism which is a top loading type or a return type according to the paper loading arrangement. However, these types of sheet feeding mechanisms must be provided with a spring or a motor for feeding papers, thereby causing printing errors due to sheet feeding errors and an increase in the manufacturing cost.
It is therefore an object of the present invention to provide an improved sheet feeding technique for separating and feeding single sheets of paper using a driving power source contained within the image forming apparatus itself.
It is another object of the present invention to provide an improved sheet feeding apparatus having a simplified and compact structure to control a sheet feeding pressure with a driving power source provided within the image forming apparatus itself.
To achieve the above objects and other advantages, there is provided a sheet feeding apparatus for an image forming apparatus having a carriage with which an ink-cartridge is mounted and which is reciprocated to print an image, the sheet feeding apparatus comprising: a printing stroke section in which the carriage is reciprocated to print an image; a feeding stroke section which is extended to one side of the printing stroke section and into which the carriage is moved whenever it is necessary to feed a new sheet; a feeding power converting unit which is disposed in a passage of the carriage in the feeding stroke section and is rotated by being in contact with the carriage; a crankshaft which is rotated in forward and reverse rotational directions corresponding to the rotational directions of the feeding power converting unit; a paper loader having one end which is rotatably disposed with respect to a hinge shaft which is apart from and faced with the crankshaft, and having another end of which is a free end; and a sheet feeding unit which is provided in at least two parts of the crankshaft and which raises the free end of the paper loader so as to generate a first feeding pressure against a feeding roller and which forcibly presses a presser for generating a second feeding pressure in order.
Further, according to the present invention, there is provided a sheet feeding method for an image forming apparatus, the method comprising the steps of: moving a carriage, in which an ink-cartridge is mounted, to a feeding stroke section; detecting whether the carriage is still moving to the feeding stroke section; determining whether a feeding power converting unit is being driven; determining whether the movement of the carriage in the feeding stroke section has completely stopped; determining whether there is a signal for a printing operation; and feeding a sheet and performing the printing operation.